| 研究実績の概要 |
The main objective of this research is to assess the hazard inside the Tokyo Bay induced from tsunamis generated by earthquakes from nearby subduction zones. The tsunami hazard assessment can be done by analyzing simulation results of tsunami propagation and sediment transportation from a set of earthquake scenarios.
We randomly generated slip distributions on the plate interface of the Sagami Trough using the Karhunen‐Loeve (K‐L) expansion method. The geometry of the plate interface is based on the Japan Integrated Velocity Structure Model (JIVSM). The magnitudes of the generated the slip distributions are from Mw 7.7 to 8.2 with 0.1 magnitude unit spacing (six magnitudes). We generated 50 slip distributions for each magnitude for a total of 300 earthquake scenarios. For each scenario, we simulated the tsunami propagation and inundation in the Tokyo Bay using high-quality and high-resolution (1 arc-sec) bathymetry and topography dataset.
We developed a numerical model that can simulate the thickness and grain size distribution of tsunami sand deposit. The numerical model was calibrated with high quality and reliable observations of tsunami inundation heights, deposit thickness and grain size distribution, topography and bathymetry data around Numanohama coast in Iwate prefecture, and a source model for the 2011 Tohoku earthquake. A model concept with three model layers of suspended sediment, deposit, and parent layers allows simulation of sediment grain size distribution and deposit thickness.
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